Gardening chat, Sept. 24, 2012

We’d like to thank David Rodriguez, County Extension Agent-Horticulture for Texas AgriLife Extension Service in Bexar County, for chatting with us today. The next chat is scheduled for 11 a.m.-noon Oct. 29. Click here to submit a question early.

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Great questions today folks!

If you need to get questions liked these answered, call our Master Gardener ‘Hotline’ at (210) 467-6575 or visit the Texas A&M AgriLife Extension Service website at: bexar-tx.tamu.edu/.

Before I leave today, here is a great educational opportunity coming up next week.

Love fruit like peaches, plums, pears, and more? Come visit with Professor and Extension Horticulturist, Dr. Larry Stein of Texas A&M AgriLIFE Extension Service to learn about selecting, growing, and maintaining a home fruit orchard. This is a great training for that backyard gardener, community garden person or that small acreage producer. Registration fee is $10 and is opened to public at 3355 Cherry Ridge, Suite 208. For more information, contact Angel Torres at 210 467-6575 or visit bexar-tx.tamu.edu

See you next month in the garden.

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Doug: I have grown some Fraxinus cuspidata, Fragrant Ash, from seed. Will they grow good in this area?

Nat: Almost every Esperanza and/or duranta plant I see is covered with flowers by this time of the year. Mine don’t have a single bud/bloom/flower. What can be done to help the plants flower, if anything? They were planted from one gallon pots in April & May and are now 4-5 feet tall.

David: Have patience. If you have them, where they are getting sufficient sunlight, they will surely soon have blossoms. They are still getting established and are devoting their energy to roots and foliage.

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Steve: Our crape myrtle has just gotten a pink bloom on it this week. In our neighborhood where there are many crape myrtles, they have been blooming pink for at least a month. Ours seems to be slow each year. What can/should we do?

David: There are countless varieties of pink crape myrtles and each variety, even each crape myrtle, is an individual with its own genetic traits. On top of this, climatic conditions will cause the variation of the initiation of blossoms. There is really nothing that you can do to alter this short of the replacement with another tree. Ensuring that it is stress free (sufficient moisture and fertilizer) will allow it to bloom on a more regular basis.

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Fred: I have an older crape myrtle in my back yard, and its leaves are turning yellow and falling off as if it’s already fall. This tree shares the back yard with two sweet gum trees. What should I do, is it dying?

David: I suspect that the plant is just reacting to its environment. The crape myrtle put on more leaves, during the wetter than normal spring growing season, than it can support now in the extreme heat. I would not worry. Just be sure not to let it dry out completely in the absence of rainfall.

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Carrie: We have a beautiful perennial firebush near the back of our home. The problem is it is almost 7 feet tall and at least 5 feet wide. It is full of blooms and has a beautiful shape, but it is TOO BIG! We had no idea that it would grow this large when we planted it. Any suggestions as to how to trim it?

David: You can take hedge clippers to your Firebush and cut it back to acceptable proportions. It, as you know, will freeze back to the ground each winter with freezing temperatures. Any time after that first freeze, you can cut it to the ground. If you are fertilizing the plant, you can cut back or eliminate that and it won’t grow so much.

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Jason: I planted some 5 gal pride of Barbados plants in April. They bloomed up until about a month ago and now there are only a couple of small flowers still coming out. I see other plants all around the city that are still blooming strong. Any comments or suggestions to get them to continue blooming or encourage more blooms?

David: Ideally, when perennials like these are 60 to 80% bloomed out, it’s best to cut them back about 1/3, fertilize them and replenish the organic hardwood mulch around their root system. This should have been done around mid-July to the first part of September. Being later in the season, it’s probably not best to cut them back that hard, because the new growth may not have enough ample time to harden off before the first expected frost date of mid-November. Do not hesitate to remove any of the seeds pods.

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David: I was wondering what would be the best way to deal with weeds in my Bermuda grass as we go into the fall and winter. The two main problems are spurge and crabgrass. I always see these weeds and they say not to use on Bermuda. I want to do something this fall so that the weeds do not take over the Bermudagrass and before the Bermuda goes into dormancy. I want my grass to be healthy and full in the spring and have fewer weeds.

David: Both the spurge and the crabgrass are warm season annual weeds. They are best controlled with the application of a pre-emergent herbicide to keep the seed from germinating. These pre-emergents should be applied mid to late February. The spurge is a broadleaf weed so a broadleaf pre-emergent such as Portrait should be applied in accordance with its label. The crabgrass will need a grassy weed pre-emergent such as Amaze. Again follow the application instructions on its label.

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Art: My oak tree has spider-web looking material on it. Is this a disease or just something that will take care of itself?

David: If it is webbing that is covering the trunk of the tree, it was made by a harmless insect called bark lice. As you say, it will take care of itself. See the images and information at plantanswers.com/barklice.htm.

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Allison: I have a pride of Barbados plants and would like to know if I can cut it back and when would be a good time. Also, it froze back in the winter and has come back beautiful and tall.

David: You can cut it back enough to keep it in control at any time, even now. You will prevent any new blossoms until it puts on new growth. It will freeze each winter and you can cut it to the ground after any such freeze. In the event that it does not freeze, then you should cut it to the ground anyway in the early spring before it starts to put on new growth. This will help it to stay within the bounds you want.

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Sarah: We have this Shummard Red Oak planted in our front yard in full sunlight. It is approximately 4″ at the base and 13ft. tall. It gets watered about 10 minutes 5 nights a week and 20 minutes 2 nights a week. All the leaves are turning brown and falling off. What’s causing this? Could it be the heat? We have a sprinkler system in the yard. The grass and all are doing well.

David: My guess would be that it is a combination of the heat and insufficient moisture. Turfgrass sprinklers just don’t provide the amount of water needed for trees and shrubs. If this is an established tree I recommend that you put a drip hose around the tree at the drip line (where water would fall from the outer foliage) and let it run for at least an hour once a week. If it is newly planted (within the year) put the drip hose close to the trunk.

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Pam: We want to plant fall ‘Zipper’ or ‘Cream’ peas, and our question is about fertilizer. When, what strength, etc.?

David: Prior to planting, incorporate (by tilling) about two pounds of 19-5-9 50% slow release nitrogen fertilizer per 100 square feet or 35 feet of row into the soil about 8 to 10 inches deep. Since peas have the ability to get nitrogen from the air as well as from the soil, no additional fertilization should be required.

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Steven: I have a new raised flower bed made of natural stone blocks with 12 inches of potting soil. What I would like to know is what type of annuals will do well with only 4 to 5 hours of full sun? I get full sun roughly from 1 to 5 pm. I currently have some Pentas in it and they are doing great. I really like marigolds and zinnias; will they do grow well with in part shade?

David: Annual red salvia, periwinkle, wax-leaf begonia, petunia (wave series, Laura Bush, VIP), coleus are some that should do fine. Fall marigolds should do fine but zinnia would be iffy because of its susceptibility to powdery mildew.

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Eric: My cucumbers grow to about one inch long, and then turn brown and die. What is the problem?

David: It takes two to tango. This, in all likelihood, means that there are no male flowers on the vine. If you can keep them alive in this weather, hopefully they will begin to have both male and female flowers on the plants. The plants will open at the same time for the bees to pollinate the female flowers and then the cucumbers will grow.

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Nancy: I read that the ‘Texas Lilac’, Vitex agnus-castus should be cut to the ground in late winter. Is this true?

David: The manner of growing Vitex is promoted so that those who desire repeat blooms can reach the old, spent blossoms and clip them off, thus stimulating more. It is not necessary if you desire the plant to grow into tree form rather than as a multi-trunk shrub.

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Sam: For the Central Texas area, how much watering does my pecan tree need during these next two dry months? A nursery worker told me, do not over-water because that leads to mildew. And the bark seems to be more cracked than some other trees I have seen in the neighborhood. Does the soil need amending? I am cutting some clusters of pecans off of the limbs hanging almost to the ground.

David: I feel sure that the bark is just the natural growth of the pecan tree. While the following information is directed to commercial growers it also applies to your trees for quality production: “Rainfall, even in the most humid areas, is erratic in distribution, and there are critical times in the season each year when trees must receive enough water to grow and fill out the nut. Mature bearing trees require 2 inches per week, and should ideally be irrigated every week or at least never be allowed to go longer than 21 days without water.” You may need to continue to cut some of the nut clusters off to prevent limb breakage. I doubt that your soil needs amending and this late in the growing season, I do not think that you need to worry about mildew.

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Shawn: We have a beautiful perennial firebush near the back of our home. The problem is it is almost 7 feet tall and at least 5 feet wide. It is full of blooms and has a beautiful shape, but it is TOO BIG! We had no idea that it would grow this large when we planted it. Any suggestions as to how to trim it?

David: You can take hedge clippers to your Firebush and cut it back to acceptable proportions. It, as you know, will freeze back to the ground each winter with freezing temperatures. Any time after that first freeze, you can cut it to the ground. If you are fertilizing the plant, you can cut back or eliminate that and it won’t grow so much.

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Shelly: I was wondering what would be the best way to deal with weeds in my Bermuda grass as we go into the fall and winter. The two main problems are spurge and crabgrass. I always see these weeds and they say not to use on Bermuda. I want to do something this fall so that the weeds do not take over the Bermudagrass and before the Bermuda goes into dormancy. I want my grass to be healthy and full in the spring and have fewer weeds.

David: Both the spurge and the crabgrass are warm season annual weeds. They are best controlled with the application of a pre-emergent herbicide to keep the seed from germinating. These pre-emergents should be applied mid to late February. The spurge is a broadleaf weed so a broadleaf pre-emergent such as Portrait should be applied in accordance with its label. The crabgrass will need a grassy weed pre-emergent such as Amaze. Again follow the application instructions on its label.

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Stan: I have planted seed from dried Pride of Barbados pods many times and they never seem to germinate. At the present time I have three small cups, each planted with three or four Pride of Barbados seeds. I have kept the soil moist and the cups get strong morning sun. Do they need to dry out? Do you think they need more sun? I thought surely the 90+ weather would bring about sprouting, but no luck so far.

David: Make sure that the seed that you are planting are nice and plumped out (not flat) as during droughty times many of the seed do not mature to viability. If they look good, soak them in water for at least 24 hours or nick the seed coat with a file or sand paper. Then plant them no more than 1/4 inch deep in good, moist potting soil. Put in a shady location and only add water to keep barely moist. They should germinate within 15 days.

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Hello everyone,

My name is David Rodriguez  Horticulturist with Texas A&M AgriLife Extension Service  and welcome to today’s “Live Gardening Chat.” Fall is here now and “Fall is for Planting.” This is the best time to rejuvenate and plant new plant material. We have had well needy rainfalls and much cooler weather, so let’s all get outside and do some gardening.